OS X Mavericks 10.9 DP1 has been released, if you need to make an installation USB drive, you can refer to the following tutorials:
First you need to turn on the ability to show hidden files. Execute the following command in the terminal (Terminal) app:
Defaults write Com.apple.Finder appleshowallfiles YES && killall Finder
Then download the OS X Mavericks installation package from the app Store and you'll find the app in the application folder named ' Install OS X 10.9′ ' after the download is complete. Now, right-click on it and select Show Package Contents.
Enter Contents/sharedsupport, and in this folder you will see a file named InstallESD.dmg. Then double-click it and mount him as a disk.
You will see a file called BASESYSTEM.DMG in the disk directory that was just mounted successfully.
Next Open "Disk Utility", restore BASESYSTEM.DMG to the USB flash drive (This step is similar to the previous method, just "source disk" must choose BASESYSTEM.DMG, Target disk or select USB drive).
After the recovery is complete, open the USB drive directory (the default name is ' OS X Base System ') and then go to the system/installation. Here you will see an alias for the installation package (similar to a shortcut with a small arrow icon on it). Please remember to delete this alias. 、
Then copy all the files in the INSTALLESD directory that you mounted (that is, the directory where you found the basesystem.dmg file) to the System/installation folder on the USB flash drive, which is primarily for the purpose of INSTALLESD Mount the installer in the directory to replace the one you just deleted from the USB drive.
The production is complete, now your USB stick should be ready to start. After inserting the USB flash drive, press and hold the option key to boot, then select the USB key to boot in the Select Startup Disk interface.
Finally, if you want to cancel the display of the hidden file, please re-execute the first step and change YES to NO on the command.